'''
生成器-笛卡尔积
迭代向前，只产生一个列表
'''
colors = ['black', 'white']
sizes = ['S', 'M', 'L']
for tshirt in ('%s %s' % (c, s) for c in colors for s in sizes):
    print(tshirt)

if __name__ == '__main__':
    print(1)
